Interceptor I-10k

[LoneWolf TN]

I recently bought an Interceptor I 10k from Justin for a fair price, and I got it assembled and up in the air. I have a perfect 1 swr, 50 ohms and x is 2. I raised the antenna up to 36' and with the radio on still a flat 1 swr, but when I turn the D&A Warrior 1000 linear on the swr goes to about a 2 when I key up and when I talk the swr swings backwards to about a 1.1??? I retuned the amp to no avail. What could be causing this backwards swr swing with amp on? I've never seen this before. The 10k is performing about the same as the spectrum 1600 did testing with locals about 25 miles away. But of course the materials are far superior. I will add this, I did something different with my grounding - I soldered 4ga. wire to the braid of the coax and went down the push up to a ground rod. I usually ground straight from the antenna mount to rod. I wouldn't think this would affect swr only with amp on but not with just the radio on. I never had this problem with the Spectrum 1600 up at the same heigth in the same location.
Thanks, LoneWolf TN

 

[Moleculo]

What are you using to measuring SWR with amp on?

I'm not crazy about your idea of running wire down the push up mast. That antenna is insulated from the mast, and (going off the top of my head here) I seem to remember that the ground on the SO-239 is connected to the ground plane radials. So now, you've made a 1 wavelength wire part of the groundplane. I doubt that is causing your issue, but it's something to think about.

 

[dodirty575]

I am sure if you contact Jay in the Mohave he will be glad to help you. I have had that in more than install and found no problem, but if it bothers you contact Jay,you won't be dissapointed.

 

[jonbah]

Your amp is probably producing harmonics which is throwing the SWR meter out of wack, not the antenna. If you look at your output on a rms meter you'll notice that your power is dropping also, this is generally normal with that type of amp since they are designed for balls to the wall, drop your input power to the amp and you'll notice a forward swing on a rms meter and it will probably sound better now that the pills are not flat topping. A big carrier is not better than a big swing on AM find a happy medium. A LPF before the meter may help with the swr reading.

Good Luck
Jonbah

 

[Master Chief]

The I-10K is DC grounded and not insulated from the mast.

You ground wire to the coax braid is a bad idea. We do this for hard-line just before we enter the building or before it makes a turn, but NEVER up at the antennas!

Ground the push-up pole/tower. Use short straps between the joints if necessary.

As far as your amplifier problem, its an amplifier problem assuming the antenna is assembled correctly. I am curious what SWR meter you are using and where it is in the line. If it is between the radio and the amp, I'd say you have an amp input section problem. Maybe you need to post this in the amplifier section.

 

[Moleculo]

The I-10K is DC grounded and NOT insulated from the mast

Yes...I went over to Jay's website and looked at the close up photo of the matching section...it is DC grounded. If it were me, I'd take the time to lower the antenna and get rid of that ground wire.

BTW, with this amp issue....are you having any problems with the output power from the amp? If not, I'd just leave it alone and use it. A 2:1 input SWR, while not perfect, probably isn't that big of a deal. If you're radio isn't cutting the power back, just have fun and forget about it.

 

[LoneWolf TN]

s

Mole, are you saying don't ground the antenna to the ground rod at all? Or are you saying undo the ground connection attached to braid of coax and reattach it to the antenna mount. Even though it is DC grounded I should still have a ground from mount to ground rod right?
Anyway, this is very strange. I have the 10k mounted exacty like I had the Spectrum mounted - everything - amp, radio, meter, coax etc. Everything but the ground to the coax braid, I did not do it that way before. I have never seen a swr/carrier @ about 2.0 swing backwards to a 1.1 when modulating. That is why I thought maybe something wasn't hooked up correctly on the 10k. I'll drop the push up pole and redo the ground wire to the mount and see what happens. Until then I won't worry too much if the swr is 1.1 when I talk.

Thanks, LoneWolf TN

 

[Moleculo]

What we're all saying is take the ground wire off the coax braid. The antenna mount is already contacting the push up pole, so it has ground. All you need to do is ground the push up pole at the base, or if you're concerned that the push up joints don't have good connection, then you can put ground strap at each joint, as MC said.

 

[LoneWolf TN]

s

Understood.

Thanks

 

[Jerry Grandstaff]

I ran a #4 copper wire from the antenna mount to the grounding rod so I know the antenna is grounded. I would think that if you use a pushup mast that grounding it at the bottom would be be as good due to the joints.

Jerry

 

[sleepwalker]

i drove a 8 foot pipe into the ground leaving about 2 feet above ground then slid the telescoping mast over it and drilled through and through and bolted them together....with a 300 watt carrier my SWR is 1.2 on 80 channels

 

[LoneWolf TN]

f

I hear you all about the grounding. I have always grounded my base antennas to ground rod. Something must have gone wrong with my D&A, because like I said - I have never had a backwards SWR swing. DK SWR = 2.0 swinging backwards to around a 1.1 when modulating. Maybe I'll get some input in the tube amp section.

Thanks for the input, LoneWolf TN

 

[FL Native]

have you remove the wire from the shield of coax yet ?

:?

 

[Marconi]

LoneWolf, what is the DK wattage into your amp?

What happens with the wattage (not SWR) when modulating with the amp in line and the amp on standby?

Do the same check with the amp out of line.

 

[smalltiredart]

If your seeing that kind of back swing, your dead key out of the amp is to high. Lower the dead key of your radio into the amp.

Marconi hit it right on the head.